Power factor correction circuit

Abstract

The invention discloses a power factor correction circuit. The power factor correction circuit comprises a rectifier circuit, a boost conversion circuit and a load circuit. The rectifier circuit is used for converting an alternating-current voltage into a direct-current voltage. The rectifier circuit comprises a first output end, a second output end and a third output end. The boost conversion circuit is used for boosting the direct-current voltage and outputting the direct-current voltage. The boost conversion circuit comprises a first input end, a second input end and a fourth output end. The fourth output end of the boost conversion circuit is connected with the first output end of the rectifier circuit. The first input end is connected with the second output end. The second input end is connected with the third output end. The load circuit is connected in series between the first output end of the rectifier circuit and the third output end. According to the technical scheme of the invention, the correction of the power factor is realized by adopting the boost conversion circuit, while the working efficiency is improved at the same time. The power factor value reaches more than 99%.

Description

technical field [0001] The present invention relates to the technical field of power supply, in particular to a power factor correction (Power Factor Correction, PFC) circuit. Background technique [0002] The front-stage input of traditional AC (alternating current) / DC (direct current) power converters generally adopts a full-bridge diode uncontrolled rectification method and a high-voltage large filter capacitor to obtain a stable DC voltage. Although the uncontrolled rectification circuit is simple and reliable, the filter capacitor will cause harmonic current interference, which will distort the AC voltage and current at the input end, resulting in a grid-side power factor of only about 0.6, which affects the normal operation of the grid. Therefore, it is necessary to Set up the power factor correction (PFC) circuit. In the single-phase PFC circuit, the Boost (switching DC) circuit is widely used because of its simple structure, easy control, and high conversion efficie...

AI Technical Summary

Problems solved by technology

[0003] However, in high-power occasions, the factors that affect the circuit efficiency are: 1) Since all semiconductor devices work in the hard switching mode, the switching loss is large; especially when it works in the state of continuous inductor current (CCM), the freewheeling diode The hard switch of the existing reverse recovery problem

As the output voltage and switching frequency increase, the loss caused by the reverse recovery current becomes larger, and the electromagnetic noise is also very serious; 2) At any time, there are always three semiconductor devices that are turned on, and the on-state loss of the power supply is large

[0004] Specific as figure 1 The existing power factor correction circuit diagram shown in the figure, the diodes (a1, a2) are removed in the figure, and the inductors (Ln1, Ln2) all use a single inductor as a traditional Boost PFC circuit. Whether it is a positive half cycle or a negative half cycle in the circuit, the output power is passed through The rectifier bridge is connected to the input bus, and due to the special position of the inductance, it will generate high common-mode interference, thereby reducing the output power factor

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